Abstract
The dose-response relation of abnormal intestinal crypt-cell enlargement has been observed after X-ray doses from 500-10 000 r. Enlargement of the largest intestinal crypt cells is a function of X-ray dose, being greater with increasing dose. Greatest enlargement was observed 48-60 hours after all doses studied. Analysis of a number of cell populations showed that cell loss from the crypt region by death and by migration on to the villus is accompanied by abnormal crypt-cell enlargement and possibly migration of the villus-core stroma into the crypt region. Greatest enlargement 48-60 hours after all doses is interpreted as a result of cell migration into an environment that does not support growth. Experiments using tritiated thymidine indicate that crypt-cell enlargement is not associated with polysomaty of the largest abnormally-enlarged cells. Abnormal crypt-cell enlargement has been considered as a possible result of water uptake, polysomaty, or unbalanced growth.